Field of the Invention
This invention refers to a reinforced safety glass and its manufacturing procedure. Although it may have diverse applications, its purpose arises from the need for safety glasses of high resistance in order to increase the safety of vehicles' occupants.
Description of the Related Art
The current status of the art involves diverse combinations of materials and procedures to obtain armored glasses. Common materials used are:
a) Polyvinyl butyral films (herein after referred to as “PVB”). Example: PVB films manufactured by Kuraray Arg.
b) PolyEthylene Terephthalate films (hereinafter referred to as “PET”), generally Crystallizable PolyEthylene Terephthalate because of its high transparency (hereinafter referred to as “C-PET”). Example: PET films manufactured by Kuraray Arg.
c) PolyUrethane films (hereinafter referred to as “PU”). Example: PU films manufactured by Dayplas S.A.
d) Safety films with adhesive, such as those manufactured by Llumar, 3M, Madico, Johnson & Johnson, Sunguard, etc.
e) Safety films without adhesive, such as those also manufactured by Llumar, 3M, Sunguard, etc. or safety films with adhesive from which the adhesive is eliminated.
f) Obviously, special glasses or original glasses used for this application.
Each of these materials have diverse densities and one or more layers may be used. The goal to obtain successful and pragmatic results for each need is based on the combination of films and especially on the procedure by which these films are combined with glasses. This is where this invention stands out and where the pillars which provide the basis for this patent application lie.
Furthermore, there are operating aspects such as a higher economy and flexibility of procedures, together with the impact of such procedures on the environment, which could not be solved to date.
In accordance with what has been analyzed above, here follow some antecedents for information purposes:
a) European Patent No. EP1322467B1 “INTRUSION RESISTANT GLASS LAMINATE” granted on Nov. 28, 2007. It consists of a laminated glass composed of: a first PBV film+a first PET film+a second PET film+a second PBV film, all of these inserted between two glasses. These films are placed between two glasses as usual.
Aside from the details of the procedure, in this case two PET films are placed between PBV films, all of which is placed between two glasses, that is to say, two glasses are needed.
b) U.S. Pat. No. 5,569,537 “Laminated glass with polyurethane resin layer and silane coupling agent layer” granted on Oct. 29, 1996. This patent protects laminated glass with polyurethane films which requires an adhesive agent. It is based on the chemical aspects of the silane agent.
c) U.S. Pat. No. 5,445,890 “Bullet resistant glass/glass, glass/plastic, and plastic/plastic laminate composites” granted on Aug. 29, 1995. This patent protects a composite of laminated glass which comprises at least 2 glasses bonded by a layer of adhesive polyester. It may or may not include a “plastic” film between the two glasses, bonded by adhesive polyester.
d) U.S. Pat. No. 4,241,140 “Laminated safety glass with polyurethane film”, granted on Dec. 23, 1980. It specifically protects polyurethane film used for safety glasses.
e) U.S. Pat. No. 4,075,386 “Security film for shatterproofing windows” granted on Feb. 21, 1978. This patent refers to a method of applying films with adhesive and watery detergent. It comprises the basic concept of safety films.
f) PCT Patent Application WO2003006240 A1 “Compositor interlayer for laminated glass” published on Jan. 23, 2013. This application claims the joint use of PU and PVB without considering a key aspect of the procedure modified by this application.
i) U.S. Pat. No. 4,594,290 “Impact resistant laminate” granted on Jun. 10, 1986. It refers to a laminate with high ballistic resistance. It uses glass, PU, PMMA and PC.
Although we have seen great progress in safety glasses in the last decades, a correct combination of films without adhesive which only requires a single glass, offering exceptional characteristics regarding resistance to impact, high transparency and low impact on the environment, could not be achieved yet. These are the key aspects of this invention.